Hello, On Mon, Jul 6, 2020 at 9:38 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > On Mon, Jun 29, 2020 at 09:49:38PM -0700, Rajat Jain wrote: > > The "ExternalFacing" devices (root ports) are still internal devices that > > sit on the internal system fabric and thus trusted. Currently they were > > being marked untrusted. > > > > This patch uses the platform flag to identify the external facing devices > > and then use it to mark any downstream devices as "untrusted". The > > external-facing devices themselves are left as "trusted". This was > > discussed here: https://lkml.org/lkml/2020/6/10/1049 > > Use the imperative mood in the commit log, as you did for 1/7. E.g., > instead of "This patch uses ...", say "Use the platform flag ...". > That helps all the commit logs read nicely together. > > I think this patch makes two changes that should be separated: > > - Treat "external-facing" devices as internal. > > - Look for the "external-facing" or "ExternalFacing" property on > Switch Downstream Ports as well as Root Ports. > > > Signed-off-by: Rajat Jain <rajatja@xxxxxxxxxx> > > --- > > v2: cosmetic changes in commit log > > > > drivers/iommu/intel/iommu.c | 2 +- > > drivers/pci/of.c | 2 +- > > drivers/pci/pci-acpi.c | 13 +++++++------ > > drivers/pci/probe.c | 2 +- > > include/linux/pci.h | 8 ++++++++ > > 5 files changed, 18 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c > > index d759e7234e982..1ccb224f82496 100644 > > --- a/drivers/iommu/intel/iommu.c > > +++ b/drivers/iommu/intel/iommu.c > > @@ -4743,7 +4743,7 @@ static inline bool has_untrusted_dev(void) > > struct pci_dev *pdev = NULL; > > > > for_each_pci_dev(pdev) > > - if (pdev->untrusted) > > + if (pdev->untrusted || pdev->external_facing) > > I think checking pdev->external_facing is enough for this case, > because it's impossible to have pdev->untrusted unless a parent has > pdev->external_facing. Agree. > > IIUC, this usage is asking "might we ever have an external device?" > as opposed to the "pdev->untrusted" uses, which are asking "is *this* > device an external device?" Agree. > > > return true; > > > > return false; > > diff --git a/drivers/pci/of.c b/drivers/pci/of.c > > index 27839cd2459f6..22727fc9558df 100644 > > --- a/drivers/pci/of.c > > +++ b/drivers/pci/of.c > > @@ -42,7 +42,7 @@ void pci_set_bus_of_node(struct pci_bus *bus) > > } else { > > node = of_node_get(bus->self->dev.of_node); > > if (node && of_property_read_bool(node, "external-facing")) > > - bus->self->untrusted = true; > > + bus->self->external_facing = true; > > } > > > > bus->dev.of_node = node; > > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c > > index 7224b1e5f2a83..492c07805caf8 100644 > > --- a/drivers/pci/pci-acpi.c > > +++ b/drivers/pci/pci-acpi.c > > @@ -1213,22 +1213,23 @@ static void pci_acpi_optimize_delay(struct pci_dev *pdev, > > ACPI_FREE(obj); > > } > > > > -static void pci_acpi_set_untrusted(struct pci_dev *dev) > > +static void pci_acpi_set_external_facing(struct pci_dev *dev) > > { > > u8 val; > > > > - if (pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT) > > + if (pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT && > > + pci_pcie_type(dev) != PCI_EXP_TYPE_DOWNSTREAM) > > This looks like a change worthy of its own patch. We used to look for > "ExternalFacingPort" only on Root Ports; now we'll also do it for > Switch Downstream Ports. Can do. (please see below) > > Can you include DT and ACPI spec references if they exist? I found > this mention: > https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports > which actually says it should only be implemented for Root Ports. I actually have no references. It seems to me that the microsoft spec assumes that all external ports must be implemented on root ports, but I think it would be equally fair for systems with PCIe switches to implement one on one of their switch downstream ports. I don't have an immediate use of this anyway, so if you think this should rather wait unless someone really has this case, this can wait. Let me know. > > It also mentions a "DmaProperty" that looks related. Maybe Linux > should also pay attention to this? Interesting. Since this is not in use currently by the kernel as well as not exposed by (our) BIOS, I don't have an immediate use case for this. I'd like to defer this for later (as-the-need-arises). > > If we do change this, should we use pcie_downstream_port(), which > includes PCI-to-PCIe bridges as well? Sure, can do that. > > > return; > > if (device_property_read_u8(&dev->dev, "ExternalFacingPort", &val)) > > return; > > > > /* > > - * These root ports expose PCIe (including DMA) outside of the > > - * system so make sure we treat them and everything behind as > > + * These root/down ports expose PCIe (including DMA) outside of the > > + * system so make sure we treat everything behind them as > > * untrusted. > > */ > > if (val) > > - dev->untrusted = 1; > > + dev->external_facing = 1; > > } > > > > static void pci_acpi_setup(struct device *dev) > > @@ -1240,7 +1241,7 @@ static void pci_acpi_setup(struct device *dev) > > return; > > > > pci_acpi_optimize_delay(pci_dev, adev->handle); > > - pci_acpi_set_untrusted(pci_dev); > > + pci_acpi_set_external_facing(pci_dev); > > pci_acpi_add_edr_notifier(pci_dev); > > > > pci_acpi_add_pm_notifier(adev, pci_dev); > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > > index 6d87066a5ecc5..8c40c00413e74 100644 > > --- a/drivers/pci/probe.c > > +++ b/drivers/pci/probe.c > > @@ -1552,7 +1552,7 @@ static void set_pcie_untrusted(struct pci_dev *dev) > > * untrusted as well. > > */ > > parent = pci_upstream_bridge(dev); > > - if (parent && parent->untrusted) > > + if (parent && (parent->untrusted || parent->external_facing)) > > dev->untrusted = true; > > } > > > > diff --git a/include/linux/pci.h b/include/linux/pci.h > > index a26be5332bba6..fe1bc603fda40 100644 > > --- a/include/linux/pci.h > > +++ b/include/linux/pci.h > > @@ -432,6 +432,14 @@ struct pci_dev { > > * mappings to make sure they cannot access arbitrary memory. > > */ > > unsigned int untrusted:1; > > + /* > > + * Devices are marked as external-facing using info from platform > > + * (ACPI / devicetree). An external-facing device is still an internal > > + * trusted device, but it faces external untrusted devices. Thus any > > + * devices enumerated downstream an external-facing device is marked > > + * as untrusted. > > This comment has a subject/verb agreement problem. I assume you meant s/is/are/ in last sentence. Will do. Thanks, Rajat > > > + */ > > + unsigned int external_facing:1; > > unsigned int broken_intx_masking:1; /* INTx masking can't be used */ > > unsigned int io_window_1k:1; /* Intel bridge 1K I/O windows */ > > unsigned int irq_managed:1; > > -- > > 2.27.0.212.ge8ba1cc988-goog > >
